ES-2053186 (EP-0489012) discloses a pressure cooker of the type with two superimposed handles, the lid one and the pan one, which has a safety device actuated by means of an operating button that slides towards a locking member provided with a pin which engages in an outward bent rim of the pan. The locking pin is held engaged by means of the force of a coaxial spring. A valve stem lifted by the pressure in the pan stops the locking member from being retracted, so the lid cannot be turned as long as there is any residual pressure in the pan. The locking device also prevents the pressurizing of the cooker in the event of the two handles not being aligned properly because in that case the locking member cannot be moved forwards to engage with the pan. To open the cooker after cooking, the valve stem drops under its own weight from its lock position and the operating button can then be retracted, the lid handle disengages from the pan and the lid can be turned for opening. The locking member of the known device is housed inside the lid handle and it is L-shaped with the long arm arranged horizontally, which obstructs the valve stem in the "release", condition and prevents it from rising.
DE-2705712 discloses a lid locking device on a pressure cooker comprising an actuating button and a mechanism for transmitting the movement to the locking member, which is pivoting.
DE-3623546-A discloses a pressure cooker with a safety device housed in the handle, which has a vertical sliding pushbutton provided with a return spring and a mechanism for stopping the lid from turning through the assistance of a valve cone for pressurizing the cooker pan. The lock actuating member pivots under the pressure of the pushbutton, and it has two ends, one of which engages on the pan rim so that the lid is left free to turn, while the other end is connected directly to the valve cone, for raising it from its seat and the consequent depressurizing of the pan.